<?php 


# 定义变量
$_11223 = 1
echo '$_11223'.PHP_EOL

$a = "haha"
echo '$a'.PHP_EOL

$b = true
print "$b".PHP_EOL

$c = -1

print "$c".PHP_EOL

$array = ['a' => 1, 'b' => 2, 'c' => 3];

$keys = array_keys($array);
$values = array_values($array);
$length = count($array);

for ($i = 0; $i < $length; $i++) {
    $key = $keys[$i];
    $value = $values[$i];
    echo "Key: " . $key . ", Value: " . $value . "\n";
}


foreach ($array as $key => $value) {
    echo "key: $key, value: $value\n";
}